This invention relates generally to sequencing valves for coupling a plurality of outlet conduits in sequence with a single supply line through which a fluid under pressure, such as water, is provided. More specifically, this invention relates to an improved sequencing valve particularly for use in an irrigation sprinkler system wherein the sequencing valve operates in response to a selected relatively low water pressure in a water supply line and wherein the valve operation is substantially unaffected by the relative elevational position of the sequencing valve in the system.
Sequencing valves in general are known particularly for use in an irrigation environment for coupling a single water supply line sequentially with a plurality of outlet conduits each including a series of irrigation sprinklers installed along its length. Such sequencing valves typically comprise a valve housing having one inlet port for connection to the water supply line and a plurality of outlet ports respectively coupled to the plurality of outlet conduits, wherein the inlet port and the outlet ports open into a common chamber within the housing. A valve disk is carried within the chamber generally between the inlet port and the plurality of outlet ports, and this valve disk has a flow opening therein for permitting water flow from the inlet port to one of the outlet ports. The valve disk is mounted for reciprocating and indexing motion toward a seated position over the outlet ports in response to the pressure and flow rate of water in the supply line when the water supply is turned on and away from the outlet ports in response to a spring force when the water supply is turned off. Accordingly, each time the water supply is turned on and off, the valve disk reciprocates and indexes with respect to the outlet ports to align the flow opening in sequence with the plurality of outlet ports such that irrigation water is supplied in sequence to the outlet conduits. This turning on and off of the water supply is accomplished by operation of an on-off valve positioned between the sequencing valve and the water supply, wherein the on-off valve can be operated manually or in response to a clock-controlled solenoid or the like. For examples of sequencing valves of this general type, see U.S. Pat. Nos. 3,460,560; 3,642,022; 4,034,775; 4,125,124; and Re. 29,252.
Sequencing valves of the general type described advantageously permit supply of water to several irrigation zones, which can be remotely located, in response to operation of a single on-off valve which can be located at any convenient, readily accessible position. For example, in an irrigation sprinkler system for a golf course or the like, the sequencing valve and its associated outlet conduits can be installed at a selected location on the course wherein the outlet conduits distribute water respectively to the irrigation zones. The sequencing valve is supplied with water via a single water supply line which is interrupted at a convenient position by the on-off valve. The on-off valve is appropriately turned on and off to vary the water pressure in the supply line thereby causing the sequencing valve to couple the water supply in sequence to the several outlet conduits.
A variety of problems and disadvantages, however, have been encountered with sequencing valves of this general type. For example, when the water supply is turned on, the flow opening in the valve disk permits a substantial flow rate of water to pass therethrough without forcing the disk toward the desired position seated over the outlet ports, whereby a relatively high flow rate is required to obtain the desired valve disk movement. In addition, when the water supply is turned off, the valve disk can be subjected to a significant fluid back pressure as a result of water remaining within the supply line and/or an outlet conduit when the sequencing valve is located in the irrigation system at an elevation which is low relative to one or more irrigation circuits to which outlet conduits are connected. Since this back pressure can lock the valve disk in a seated position over the outlet ports to prevent the desired reciprocating and indexing valve disk movement, use of the sequencing valve has been limited to irrigation systems wherein the sequencing valve can be installed at a relatively high terrain elevation. Still further, prior art sequencing valves have not provided any externally visible means for determining which outlet port will be next connected with the water supply line, nor have these sequencing valves provided any externally accessible adjustment means for permitting selection of the outlet port to be connected next with the water supply line.
In an effort to improve the response characteristics of the valve disk to relatively low water flow rate, it has been proposed to provide a pressure-responsive valve for temporarily closing the valve disk flow opening when the water supply is turned on thereby to prevent water flow through the flow opening until the valve disk reaches a seated position over the outlet ports. See, for example, U.S. Pat. No. 3,524,470 which provides pressure-responsive resilient flaps formed integrally with a resilient valve disk. However, while such devices improve low flow rate valve disk response, they have not been adapted to meet a variety of different operating conditions responsive to different water flow rates and/or pressures without requiring major modifications or substitution of parts. Moreover, these sequencing valves have not addressed the problem of fluid back pressure when the sequencing valve is installed in an irrigation system at a relatively low terrain elevation. Still further, no externally accessible or visible structures have been provided for indicating or for permitting selection of the next outlet conduit to be connected to the water supply line.
The present invention overcomes the problems and disadvantages of the prior art by providing an improved sequencing valve having a valve disk adapted for movement toward and away from a plurality of outlet ports in response to selected operating conditions, wherein valve disk movement is substantially unaffected by relative terrain elevation. Moreover, the position of the valve disk relative to the outlet ports is visually indicated and adjustable from the exterior of the sequencing valve.